Impregnating paper making felts with polyvinyl alcohol containing emulsion



Patented Sept. 20, 1949 IMPREGNATING Par-Ea MAKING Farms 7 WITHPOLYVINYLALCOHOL' CONTAIN- ING'EMULSION Orion William Berglund, Dayton,Ohio, assignor to The Orr Felt & Blanket Company, Piqua, Ohio, acorporation of Ohio No Drawing. Application October 24, 1946, Serial No.705,500

6 Claims. (01. 117-140) UNITED STATES PATENT omen;

' This invention deals with a method of treatupon the pH of rubberemulsion and upon the ing felts for paper making or like machines andacid content of the felt. with the articles obtained thereby. Theaddition of curing catalysts, such as It is an object of this inventionto provide felts diammonium phosphate, tartaric acid or the like forpaper making or like machines that have a was also found to beadvantageous. high abrasion resistance. In the following table a numberof experiments It is still another object of this invention to arecompiled in order to illustrate, but not to provide felts for papermaking or like machines limit, the object of my invention.

Example -t I II III IV v a v1 Aqueous resin (come. 60%)"... 80 g. ureaionn- 80 games iormwflgaurea form- 33 gaurea form- 80 g. acrylonitrile80 g. polyvinyl aldehyde resin. ehyde resin. ehyde resin. ehyde resin.bultadiene cobutytal po ymer. Polyvinyl alcohol g 20 g 60 20 20 g. Cone.of resin (rubber) Poly- 12.75% 12.75% l 12%. vinyl alcohol mixture. m

Tartaric acid Pick-up 12% 12%.

Curing tenlperatu 225 F. 225 F Curing time 3 hrs. 3 hrs.

Increase of abrasion resistance. 67%. 7 33? 7 Water pick-n 7 7 232%.

p Water retention after H20 re- 1007 moved by mechanical means. Waterdiflcrential 123% 141%.

that have a high absorptive capacity for water. The process used forimpregnating the felts was The a d o h r o s ar a complished by the samein all instances. The felt was immersed i p i the felts wi h m x of pyinto the aqueous mixture, the excess removed by Vinyl 111001101 and anaqueous 81111115101101 Soiumechanical means such as by squeezing orcention of synthetic rubber or synthetic resin and trifuging and timpregnated felt cured t curing 531d mixture on the feltsafter,preferably at a temperature of from 200 to As resins, all water solubleand water emulsi- R for substantially 3 flable resins were foundsuitable; in particular, The impregnation may, of course, be carried Iout by any other means known in the art; thus urea formaldehyde resinand phenol formaldehyde resm in aqueous Solution and polyvinylapplication by spraying was equally satisfactory. It will be seen fromthe test results listed in butyral suspended in water were foundsatisfactory. Among the rubbers, acrylonitrlle butadime copolymer wasfound preferable; however, the tablev that the abrasion resistance wasinother synthetic latices are also operative with creased by as much asfrom 67% to 133% and satisfaction that the water differential rangedfrom 115% to The felts usually contain more or less acid as high as222%. Due to this factor, the service originates from pretreatingprocesses: was considerably enthanced the treatment neutralization ofthis acid is necessary in order according to this inventlon- The Waterdiffer to obtain uniform impregnation of rubbers to ential is a goodindicator for h efi n y 0! the felts. If the acid is not neutralized,the the felts inremeving the water m p per pulp. impregnating solutionwill change from its alkali It will be understood that while there havestate to an acid state and the rubber or latex will been describedherein certain Specific embodiprecipitate or kick-out and be of no valueas an me s of he invention. it is not intended e y impregnant. For thisreason the impregnating have it limited to circumscribed y h demulsions. are preferably given a pH above 7; tails given, since theinvention is susceptible to this may be done by any alkaline solution. Ivarious modifications and changes which come have used ammonia solutionwith advantage for within the spirit of the disclosure and the scopethis purpose. The amount of alkali is dependent 56 of the appendedclaims.

' merized mixture consisting of 4 3 I claim:

1. In a method of making felts for paper mak- 2. As a new article ofmanufacture, a felt for paper making or like machines, said-felt helngimpregnated with to'25% of its weight-"0f a polymerized mixtureconsisting of fromwfliifi parts of polyvinyl alcohol and from 80-33 ofacrylonitrile butadiene copolymer. c

3. As a new article of manufacture, a; felt A paper making or like,machines, said i'eltbeing' impregnated with 11 to 15% of its weighti'ot;h V

to 225? F, for approxipolymerized mixture consisting of from we? partsof polyvinyl alcohol and from 3043 parts 1 of acrylonitrile butadienecopolymeru 4. As a new article of manufacture, a felt-for .paper makingmachines, said felt being impreg 1 1 nated with from 10 to ofits weightof apolyparts of .acrylonitrile butadiene copolymer and 1 part ofpolyvinyl alcohoL 5. As a new article of manufacture, a felt for papermaking or like machines, said felt being by mechanical impregnated with10 to 25% of its weight of a polymerized mixture consisting of a majorportion by weight of acrylonitrile butadiene copolymet and a minorportlonby weight of polyvinyl alcohol;

6. In a method of making felts for paper makof (a) impreging or likemachines, the steps consisting of a nating the felts with a mixtureminor portion by weight of polyvinyl alcohol solution and a majorportion by weight of sonic-- nitrile butadiene copolymer; (b) removingany excess of said impre nating material from the felt means so as toleave a pick-up 'of-from 10 to 25 of cured material; and (c)-curinga''aid imp n rm'm-n o I felt at a temperature of 25l for approximately 3hours.

ORlION WILLIAM BERGLUND.

1 ssumes crran esare record in the was fl',482,0.12 Howard ull-Jan. 29,192! "2,256,853 Schwartz Sept. 23,1941 2327.1259- V Schnabel'et al, Mar.24,1942 ;2, 322;88 s scnwmzar- '.."June 29,1943 2,328,957 Coulter -'Aug.31, 1943 OTHER serfno. 323,052, Holl (A; P.- co'lpubnsned May 4. i a A

